The present invention relates to a non-sealable, multi-layer polypropylene film, its manufacture and its method of use.
Sealable and non-sealable polypropylene films have been described in many publications. One problem which always arises with these films is the adhesion of coatings, prints or adhesives on this type of film, which is in most cases insufficient due to the highly nonpolar character of the polyolefins. Since environmental protection regulations are becoming ever more stringent, aqueous coating systems are gaining more and more importance, but it is precisely these types of coatings that lead to very specific adhesion problems due to their polarity.
EP-A-0,234,758 describes a polypropylene film which is said to be suitable in particular for coating with aqueous coatings. However, the great drawback of this film is that it only has good coatability shortly after its manufacture and loses it with increasing storage time. When producing laminates using this film and employing aqueous adhesives, it was discovered that the curing of the adhesives is considerably delayed on storage.